1 Unregulated, Emerging DBPs - PowerPoint Presentation

Slide1

1

Unregulated, Emerging DBPs

Why We Should Understand Them

March 26, 2018

J. Clark Maness, EI

Staff Professional, WithersRavenel

PRESENTATION

2

TOPICS

3

Why disinfect?

Needed to prevent microbial, waterborne diseases.

~ 2.4 million preventable deaths with full access to clean, reliable sanitation and drinking water (Bartram,

Cairncross

, 2010

).

https://infogr.am/poor-people-down-have-clean-water

4

Disinfection By-Products

An unintended consequence: formation of disinfection by-products (DBPs).

DBPs formed through oxidation and substitution reactions with organic matter

http://www.waterhelp.org/index.php/article/introduction_disinfection_byproduct_sampling

5

Importance of DBP Control

Why DBP control?

Carcinogenic

Mutagenic

Teratogenic

Drinking water systems will continue to disinfect the water we drink and we’re forced to balance risks.

6

Brief History of DBPs and Regulations

The Safe Drinking Water Act (SDWA) passed in 1974.

Environmental Protection Agency (USEPA) to establish and enforce drinking water standards.

Around the same time, trihalomethanes (THMs) were discovered, and subsequently regulated by the USEPA in 1979.

http://www.illienglobal.com/international-day-of-happiness-earth-day-model/

7

Brief History of DBPs and Regulations

1998: Stage 1 Disinfectants/Disinfection By-Products Rule (DBPR) regulated more DBPs and reduced acceptable THM levels

2006: Stage 2 DBPR implemented stricter monitoring requirements in distribution systems.

Today, still only 11 regulated DBPs.

4 Trihalomethanes (THM4)

5 Haloacetic Acids (HAA5)…but there are nine total HAAs (HAA9)

Bromate and chlorite (oxyhalides)

8

Brief History of DBPs and Regulations

Many utilities struggled with Stage 1 and 2 DBPR regulations.

Popular way to comply was to switch to an alternative disinfectant and/or use multiple disinfectants.

Alternative disinfectants

Chloramines (mono-, di-, & tri-)

Ozone (O

3

)

Chlorine Dioxide (ClO

2

)

Ultra Violet (UV)

9

Effect of alternative disinfectants

Positive

: The reduction of regulated DBPs

Negative

: The increased formation of emerging/unregulated DBPs

10

Emerging/Unregulated DBPs

Presently identified emerging DBP classes include: Halonitromethanes (HNMs)Halofuranones

Haloamides (HAMs)Haloacetonitrile (HANs) TribromopyrroleHaloacetaldehydes (HALs)Iodo-Haloacetic Acids (I-HAAs)Iodo-Trihalomethanes (I-THMs)Nitrosamines

More than 600 identified DBPs

11

What is an emerging DBP?

Have at least a moderate occurrence level in public drinking water systems (sub- to low µg/L)

Known or suspected to cause adverse toxicological effects in humans

Currently not regulated by the USEPA or individual state authority

12

Why care?

It’s our duty to care about the health of the public.

With

GenX

, C8, and etc. our customers are more well-informed than ever.

Regulations will likely get stricter in the future.

13

Examples

Ozone

 Bromate Formation

Reduces or removes formation of THMs and HAAs

However, leads to elevated levels of

bromate

(known carcinogen in lab animals)

Big issue if elevated levels of bromide present.

14

Examples

Chloramines

 NDMA Formation

Reduces formation of THMs and HAAs

However, leads to elevated levels of

Nitrosodimethlyamine

(NDMA)

(probable human carcinogen)

Big issue if elevated levels of tertiary amines present (think biopolymers and treatment polymers)

15

Examples

Chlorine Dioxide

 Chlorite Formation

Reduces formation of THMs and HAAs

However, leads to elevated levels of

Chlorite

(regulated DBP)

Chlorite causes anemia; nervous system damage in infants and young children)

16

Control of Emerging DBP Formation

Four (4) general options

DBP precursor material removal

Preformed DBP and precursor removal

DBP removal post disinfection

Distribution System Control

17

Control of Emerging DBP Formation

DBP precursor material removal

Activated carbon filtration

Granular activated carbon (GAC) or powdered activated carbon (PAC)

May lead to formation of more brominated/iodinated DBPs

Membrane filtration

Ultrafiltration, nanofiltration, and reverse osmosis

Expensive

Enhanced Coagulation and Sedimentation (increased TOC removal)

Increased coagulant costs

Capital cost for improved settling equipment (example: settling plates)

18

Control of Emerging DBP Formation

Preformed DBP and DBP precursor removal

Add disinfectant at different points in treatment process to preform DBPs

DBPs then removed during processes highlighted earlier

Activated carbon filtration

Granular activated carbon (GAC) or powdered activated carbon (PAC)

May actually

Membrane filtration

Ultrafiltration, nanofiltration, and reverse osmosis

Expensive

19

Control of Emerging DBP Formation

DBP Removal Post-Disinfection

Aeration (good for THM and other volatile DBP removal)

20

Control of Emerging DBP Formation

Distribution System Control

Tank aeration

Change chlorination points in system

Tank Recirculation

21

Great Resources on Emerging DBPs

Richardson, S.,

Plewa

, M., Wagner, E.,

Schoeny

, R., &

Demarini

, D. (2007). Occurrence,

genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research.

Krasner, S. W., Weinberg, H. S., Richardson, S. D., Pastor, S. J., Chinn, R.,

Sclimenti

, M. J.,

Thruston

, A. D. (2006). Occurrence of a New Generation of Disinfection Byproducts †.

Environmental Science & Technology

, 40(23), 7175-7185. doi:10.1021/es060353j

22

Great Resources on Emerging DBPs

Richardson, S., Plewa, M., Wagner, E., Schoeny, R., &

Demarini, D. (2007). Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research. Mutation Research/Reviews in Mutation Research, 636(1-3), 178-242. doi:10.1016/j.mrrev.2007.09.001